# These settings were set by the catalyst build script that automatically
# built this stage.
# Please consult /etc/make.conf.example for a more detailed example.
# turn off -ftree-vectorize and see if that helps
# hald is stiil broken
# try -O2
CFLAGS= "-march=native -O2 -pipe -fno-tree-vectorize"
CXXFLAGS="-march=native -O2 -pipe -fno-tree-vectorize"

# lets play with --as-needed
LDFLAGS="-Wl,--as-needed"

# WARNING: Changing your CHOST is not something that should be done lightly.
# Please consult http://www.gentoo.org/doc/en/change-chost.xml before changing.
CHOST="x86_64-pc-linux-gnu"

# MAKEOPTS provides extra options that may be passed to 'make' when a
# program is compiled. Presently the only use is for specifying
# the number of parallel makes (-j) to perform. The suggested number
# for parallel makes is CPUs+1.

using ccache makes build “10 to 5 times faster”. I’ll call this statement for what it is: bullshit

Of course, mentioning a factor is stupid for modern systems, since it depends very much on your CPU (and number of CPUs) and RAM.
However, unless you have an incredible powerful CPU (or an enormous number of them) as flameeyes has on his tinderbox, you will usually have a considerable speed increase - usually not for the first installation of a package (although even then compiling of bundled libs can sometimes speed up) but usually for upgrades of the packge, provided you reserved enough space for the cache (depending on your system, 4GB may nowadays be not enough unless you set CCACHE_COMPRESS).
Everybody should judge by himself, not rely on other's benchmarks in this connection.
The remark that ccache can cause problems is pure FUD. Yes, in case of powerloss or kernel panick during compiling you might get problems with the package compiled, so in such an exceptional situation you should set CCACHE_RECACHE temporarily when reemerging the package again, but that's it.

I have a similar setting, because I am building on my "main" system for several other systems. It is no problem to build the userland tools with support for all those, because it just means that several different libraries will be built - you switch between the implementations with eselect. Actually I can even use the same kernel with the same modules.d on the different machines, since the modules recognize that the corresponding other card is not available and refuse to load. However, the latter is by experiment and I would not rely on it: Better to mask in modules.d the kernel modules for the hardware you do not have.

# WARNING: Changing your CHOST is not something that should be done lightly.
# Please consult http://www.gentoo.org/doc/en/change-chost.xml before changing.
CHOST="x86_64-pc-linux-gnu"
# These are the USE flags that were used in addition to what is provided by the
# profile used for building.

# /mypath (path changed) is here, since I have replaced many config files
# with symlinks to this directory to get a backup of my config.
# Also, I want to be informed about changes of certain config files
# (Unfortunately, site-start.el and make.conf.example does not work,
# but I leave it here in case this will be fixed some day...)
CONFIG_PROTECT="/mypath
/usr/share/fonts/misc/fonts.alias
/usr/share/emacs/site-lisp/site-start.el
/var/lib/alsa
/usr/share/portage/config/make.conf.example"
EBEEP_IGNORE="true"
EPAUSE_IGNORE="true"

# xzbest is a local script which calls xz with best compression mode according to
# available memory
PORTAGE_COMPRESS="xzbest"
QUICKPKG_DEFAULT_OPTS="${QUICKPKG_DEFAULT_OPTS} --umask=022"
QUICKPKG_DEFAULT_OPTS="${QUICKPKG_DEFAULT_OPTS} --include-config=y"
QUICKPKG_DEFAULT_OPTS="${QUICKPKG_DEFAULT_OPTS} --include-unmodified-config=y"
LANG=C
LC_CTYPE="${LANG}"
LC_COLLATE="${LANG}"
LC_MESSAGES="${LANG}"

# By default, I want to reuse the local vcs data for live ebuilds (since most of
# my rebuilds are just needed after upgrades of libraries or after minor
# kernel upgrades). If I want to update the local data to the most current
# version, I use the command
# EVCS_OFFLINE= emerge ...
EVCS_OFFLINE=1
ESCM_OFFLINE="${EVCS_OFFLINE}"

CFLAGS="-march=core2 -O2 -pipe"
CXXFLAGS="${CFLAGS}"
# WARNING: Changing your CHOST is not something that should be done lightly.
# Please consult http://www.gentoo.org/doc/en/change-chost.xml before changing.
CHOST="x86_64-pc-linux-gnu"
# These are the USE flags that were used in addition to what is provided by the
# profile used for building.